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Scoot F.A.Q.


Q. What other parts or supplies will I need along with a big bore kit?
( Minarelli / 1E40QMB / Jog )

First read the F.A.Q. article HERE regarding big bore kits if you haven't already. Then review the list below.
  • Make sure you have the accessories needed to match the cylinder kit you've chose. Beyond mild street/sport level kits, many cylinders will not work well with a stock exhaust so you should get a pipe that is suitable for your new displacement and power band RPM. If using a cylinder kit intended to rev above 10,000RPM regularly, you should consider upgrading to an aftermarket crankshaft that can handle consistent high RPM. High rev cylinders may also require racing ignitions, performance CVT parts, and more to work properly and remain reliable.

  • Some cylinder kits don't include a new wrist pin bearing, but I would suggest getting one and replacing it during the big bore kit install. Larger pistons may be able to use wider wrist pin bearings. I have used a Wiseco B1043 bearing for some of my ~70cc builds on 12mm wrist pin engines if no needle bearing was included with the kit. That part number will not work with 10mm wrist pins. Stage6, Malossi, and others make quality replacement bearings and should have one available to suit your application.

  • You will need a selection of main jets to help get your carburetor in tune with the new big bore kit. Some advise a main jet as a one-size-fits-all solution. This may work well enough to get by, but I find it's best to go through a tuning process and select the jet that works best in your specific application. Too many variables such as air filter style, elevation, conditions, carburetor, and more won't allow any one jet to work the best for every application. Stock carburetors for the 1E40QMB use Mikuni VM11/22 main jets. You can buy a jet kit that covers most tuning needs at Parts For Scooters (part # 114-50). You can also find them individually or buy kits from other retailers. If you are upgrading to a different carburetor be sure to get the appropriate jets for it.

  • It may not be necessary in all cases, but you may benefit from having a selection of roller or slider weights on hand to get your CVT in sync with your new engine combo. Heavier weights may be needed to control RPM because of the additional torque that the larger displacement generates if you're using a mild big bore kit. High revving kits may require lighter weights, stiffer clutch and/or contra springs, and other CVT modifications for best results. Most 1E40QMB engines use 15x12mm roller or slider weights, but aftermarket variators may use different sizes. Tuning roller sets that include many weights can be bought cheaper than buying multiple individual sets of rollers or sliders. They're good for helping you get in tune, but these weights are not intended for regular use. They will not last long. If you use tuning roller weights you should replace them with a quality set of rollers or sliders once you figure out what weights work best. You may also consider modifying rollers or sliders to help you tune.

  • Go over the BBK Installation Tutorial and make sure you have all of the tools to complete the job.

Related Info :
Big Bore Kit Installation Tutorial
Minarelli / 1E40QMB Wrist Pin Sizes


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